When setting up SSRS, you can install Reporting Services on one server and the databases on another so missing those databases may not mean too much. They could just be on another server. You can check the other instances and see if you find the databases. From there, SSRS polls things frequently so you can see if you can get information on the Report Server connection - something basic along the lines of: 
SELECT
    s.session_id,
    c.connect_time,
    c.last_read,
    c.client_net_address,
    s.[host_name]
FROM sys.dm_exec_connections c
INNER JOIN sys.dm_exec_sessions s
ON c.session_id = s.session_id
WHERE s.[program_name] like 'Report%'

IIS doesn't really matter to SSRS anymore as it goes through http.sys starting with SQL Server 2008. So you can ignore that.
If you go to the C:\Program Files\Microsoft SQL Server\MSRS13.MSSQLSERVER\Reporting Services\LogFiles directory, that is where the ReportingServices log files are normally located. If you find some there, the naming convention is ReportServerService_<data and time stamp>.log
If the log files are there, open one up and at the beginning the initialization steps and configuration information is logged. In that file, search for the attribute <SystemName>. Those should have the server name. Not necessarily instance name but just the server.
And then if you search that file for registered url. There should be two - one for ReportServer/ and another for Reports/ and the reservation for Reports is what you are looking for.
When you try to connect, log onto the server where it's supposed to be located and right click on Internet Explorer and select run as administrator and see if that let's you connect. You normally don't get a blank page - you get things like a prompt for credentials, the main page for Report Manager or an error page.

Sue